Originally posted by DuDun:

I've only seen greydwarfs and skeletons show in different colors, not any other mob. Not the ghosts, not the swamp man, not the one eyed swamp man, not the drakes, not the wolves, not the leeches, not the plains goblin or Deathskitos neither the Sea serpent.

All starred monsters spawn larger and in a different color which is dependent on the number of stars they have. Not every monster type can spawn starred versions though, but of the ones that can they are always a different color. Of the ones you listed, leeches, draugr, wolves and fulings can be starred and change color, the others never spawn in with stars (I’m not actually sure which mob you think is the one eyed swamp man though)